I am interested in buying a yamaha yz450F but have a few questions first. I just sold a 04 Honda CRF250R and it ate valves like crazy. I changed the oil and oil filter every other ride. I cleaned the air filter after every ride.But the valve problem was awful. So how are the valves on the 450's? Are they anywhere as bad as the ones on the Honda 250's?I know the valves have to be kept in spec but how often do these need to be checked. On my 250f it seems that I was having valve problems about every other ride.Needless to say I was very unhappy with the Honda bike.